1. Field of the Invention
The present invention pertains to a protein beverage, and to methods of making the beverage.
2. Brief Description of the Background Art
This section describes background subject matter related to the disclosed embodiments of the present invention. There is no intention, either express or implied, that the background art discussed in this section legally constitutes prior art. Moreover, this brief description is not intended to fully describe the subject matter of this art, the reader is invited to more thoroughly examine the background to better understand what is disclosed.
Carbonated dairy products have been highly sought after, and several different kinds of products have been developed. One of the more serious obstacles to be overcome is production of a highly carbonated drink where, for example, the dissolved carbon dioxide gas at room temperature is at least half of the volume of the liquid product it is dissolved in without incurring separation out or precipitation of the dairy protein from the liquid during manufacture and handling, shipping and storage. In addition to manufacturability aid shelf life, the taste of previous carbonated dairy products may generally have been adversely affected by the kind of proteins present in combination with the carbonation.
Milk contains two major protein fl-actions, casein, which may provide about 80% by weight of the total protein, and whey protein, which may provide about 20% by weight of the total protein. The whey protein fraction is the protein fraction which may remain soluble when the casein fraction is coagulated (such, for example, as by either enzyme or acid) and separated as cheese curd. Whey protein may include several protein fractions, including, for example, β-lactoglobulin, α-lactoglobulin, Lactalbumin, immunoglobulins (such as IgG1, IgG2, IgA, and IgM, for example), lactoferrin, glycomacropeptides, and lactoperoxidase.
Compared to casein and soy, whey proteins may be highly soluble. Whey proteins may be the least soluble at typically about pH 4.5 to about pH 5.5, which may be the isoelectric point (the pH at which the net electrical charge is zero) for whey protein. In higher acid systems with a pH less than about 4.5, such as in many carbonated beverages, the acid solubility of whey proteins may be especially important; however, protein precipitation may occur during the mixing period when the pH of the whey protein, which typically has a pH of about 6 to about 7, transitions through the zone of isoelectric points. Protein solubility may be affected by heat, and therefore the elevated temperatures experienced during pasteurization may also negatively affect solubility and fluidity resulting in protein precipitation or gelation.
Whey protein may have a higher biological value and/or protein digestibility corrected amino acid score (PDCAAS) than casein. The physical properties of whey proteins in the digestive tract may be quite distinct from the properties of casein. Caseins may form curds within the stomach, which curds may be slow to exit from the stomach and which curds may increase their hydrolysis prior to entering the small intestine. Alternatively, whey proteins may reach the jejunum almost immediately; however their hydrolysis within the intestine may be slower than that of caseins, so their digestion and absorption may occur over a greater length of the intestine.
The protein efficiency ratio (PER) of a protein source measures the weight gain of young animals per grain of protein eaten over a given time period. Any protein having a PER of 2.5 is considered good quality. Whey protein is considered to be a nutritionally excellent protein, as it has a PER of 3.2. Casein has a PER of 2.5, while many commonly used proteins have a PER of less than 2.5, such as soy protein (PER 2.2), corn protein (PER 2.2), peanut protein (PER 1.8), and wheat gluten (PER 0.8). The higher PER of whey protein may be due in part to the high level of sulfur-containing amino acids in whey protein. Such higher level may contribute to whey protein's ability to enhance immune-function and antioxidant status.
Whey protein is a rich source of branched chain amino acids (BCAAs), containing the highest known levels of any natural food source. BCAAs are important for athletes, since, unlike the other essential amino acids, they are metabolized directly into muscle tissue and are the first amino acids used during periods of exercise and resistance training. Leucine may be important for athletes as it may play a key role in muscle protein synthesis and lean muscle support and growth. Research suggests that individuals who exercise benefit from diets high in leucine and may have more lean muscle tissue and less body fat than individuals whose diet contains lower levels of leucine. Whey protein isolate may have approximately 45% by weight more leucine than soy protein isolate.
Whey protein is available in several forms, with preparations which may range from about 1% to about 99% whey protein. Whey protein preparations may be in an aqueous form created by the removal of casein, but often takes several other forms, such as, for example, but not by way of limitation, a whey protein extract whey protein concentrate, whey protein isolate, or whey protein hydrolysate.
Whey protein concentrate may be prepared by removing sufficient non-protein constituents from whey by membrane filtration, so that the finished dry product may be selected to contain whey protein at a given concentration which may range from about 25% by weight to about 89.9% by weight protein.
Whey protein isolate may be obtained by removing sufficient non-protein constituents from whey by membrane filtration or ion exchange absorption, so that the finished dry product may contain about 90% by weight or more whey protein, and little, if any, fat, cholesterol, or carbohydrates (e.g., lactose). Prior to concentration and spray drying, aqueous whey protein isolate may have a whey protein concentration of about 1% by weight to about 40% by weight, and may also be essentially free of fat, cholesterol, and carbohydrates.
Whey protein hydrolysate is a whey protein preparation which may have been subjected to enzymatic digestion with a protease enzyme or limited acid hydrolysis, or a suitable mechanical breakage of peptide bonds to form smaller peptides and polypeptides to form smaller peptides and polypeptides. The protein concentration of the whey protein hydrolysate may be dependent upon the starting material. For example, a whey protein hydrolysate prepared from a 80% by weight whey protein concentrate may have a 80% by weight protein concentration, and a whey protein hydrolysate prepared from a 90% by weight whey protein isolate may have a 90% by weight protein concentration. Not all hydrolyzed whey proteins may behave alike in a food formulation, and thus one hydrolyzed whey protein may not be interchangeable with another. The functional and biological properties of whey protein hydrolysates may vary depending upon factors, such as degree of hydrolysis and which protease enzyme is used for hydrolysis.
Although hydrolysis of whey protein may lead to increased solubility, it may also negatively impact the taste. Whey protein typically has a fresh, neutral taste which may allow it to be included in other foods without adversely affecting the taste. However, hydrolysis of whey protein may result in a very bitter taste, which may impose a practical limit on the amount of whey protein hydrolysate that can be used in a food product. Therefore, a high protein beverage made with whey protein hydrolysate may require a large amount of sweeteners, or bitter masking agents to overcome the bitter taste. However, such a large amount of sweetener may not be desirable to many consumers or the bitter aftertaste of the high protein beverage may be difficult or impossible to mask to a satisfactory extent for some applications.
Whey protein contains all of the essential amino acids, and therefore, is a high quality, complete source of protein, where complete means that whey protein contains all the essential amino acids for growth of body tissues. Since whey protein is available in forms containing little fat and carbohydrates, it may be a particularly valuable source of nutrition for athletes and for individuals with special medical needs (e.g., lactose intolerant individuals), and may be a valuable component of a diet program. Further, since whey protein may contain biologically active proteins such as the immunoglobulins, lactoperoxidase, and lactoferrin, whey protein may provide advantages over other protein sources such as soy protein.
In an effort to increase the availability and use of whey protein, efforts have been made to include whey protein drinks among currently available dairy protein drinks. In particular, efforts have been made to include whey protein as a protein source in carbonated beverages. Unfortunately, the carbonation process may generally result in destabilization of whey protein, resulting in foaming and/or gelling problems under certain conditions. As a result, the amount of whey protein that has been included in carbonated beverages has been severely limited.
An article by V. H. Holsinger in Adv. Exp. Med. Biol. 1978; 105:735-47, titled: “Fortification of soft drinks with protein from cottage cheese whey”, describes preparation of cottage cheese whey protein concentrates which have the solubility, stability, and flavor to make them suitable for fortification of soft drinks and related products. Carbonated beverages prepared with conventional beverage ingredients and containing up to 1% by weight of the total beverage of added whey protein are said to have maintained clarity, color, and flavor during 203 days of storage at room temperature. Clarity of 1% protein solutions at a pH of 2-3.4 is said to be unimpaired by heating for 6 hours at 80 degrees (without specifying ° C. or ° F.), but some structural change was said to have occurred, since an average of 37% of the protein is said to have precipitated on shifting the pH to 4.7.
Clouding or creaming agents useful for still or carbonated beverages, especially acid types are described in U.S. Pat. No. 4,790,998, issued to Marsha Schwartz on Dec. 13, 1988, and entitled: “Beverage Cloud Based On A Whey Protein-Stabilized Lipid”. The composition of matter described comprises a whey protein-stabilized lipid emulsified in an acidic aqueous solution. The important features of the patented whey protein - stabilizing lipid are said to include the balancing of the lipid system, the use of whey protein at pH levels of less than 4.5, and heating and homogenizing the solution to achieve acid emulsification stability. All ingredients are said to be natural, i.e., unmodified from the form typically found in nature.
A Russian abstract by Kudryavtseva et al., in Molochnaya Promyshlennost 1981; 5: 45-46, with an English translated title of: “Carbonated whey beverage”, vaguely describes a method for the manufacture of a carbonated beverage involving the following major steps: filtration of tvorog whey containing less than 1.5% protein and 0.2% fat and with a tiratable acidity of less than 75 degrees Thorner, holding for up to a day at 6-8° C., heating at 90-95° C. and holding for 15 minutes, cooling to 60° C., centrifuging, addition of unnamed ingredients (not named), cooling to 4-6° C. and injection of CO2. The Abstract then suggests the product can be bottled in narrow-neck bottles and closed with crown cork closures. Subsequent storage is at less than 8° C.
Tvorog is a Russian soft farmer's cheese. Tvorog is commonly made by allowing raw milk to sour naturally. However, it may also be made by curdling raw milk by the addition of a starter bacterial culture or an acid. Once curdled, the tvorog may be filtered to separate the tvorog curds from the tvorog whey, which typically contains whey protein, fat and lactose.
U.S. Pat. No. 4,804,552 to Ahmed et al., issued Feb. 14, 1989, and entitled: “Carbonated Liquid Dairy Product and Method of Production Thereof” describes a method of carbonating a liquid dairy product to a level of “at least” 1.5 volumes of carbon dioxide dissolved in 1.0 volume of liquid dairy product, while not destabilizing the liquid dairy product. The liquid dairy product is heated to a temperature of at least 160° F. for a time not in excess of 30 minutes, whereby the indigenous dairy protein and ash therein are at least partially denatured. The denatured liquid dairy product is then cooled to a temperature of less than about 50° F. The cooled liquid is then subjected to pressurized carbon dioxide to carbonate the dairy product to provide taste and mouth feel. The product is then packaged in closed containers capable of substantially retaining the degree of carbonation. The carbonated dairy product is said to be buffered to a pH of at least 4.0 while being highly carbonated but not destabilized.
U.S. Pat. No. 6,403,129, to Clark et al., issued Jun. 11, 2002, and entitled: “Carbonated Fortified Milk-Based Beverage And Method Of Making Carbonated Fortified Milk-Based Beverage For The Supplementation Of Essential Nutrients In The Human Diet”, discloses dairy or non-dairy based fortified carbonated beverage solutions that supply nutrients in the human diet. The beverage described is said to have carbonation to enhance taste, improve body and mouth-feel and aid in the stabilization of milk protein such as Lactalbumin and Casein.
U.S. Pat. No. 6,761,920 to Jeffrey Kaplan, issued Jul. 13, 2004, and entitled: “Process For Making Shelf-Stable Carbonated Milk Beverage”, describes an aerated or carbonated milk product drink made using a method which includes pre-heating, pressurized ultra-heat treating, subsequent carbonation with a gas or gases under pressure, and packaging into a container. The method of producing the shelf-stable carbonated milk product comprises injecting under pressure carbon dioxide gas or a mixture of gases into the milk product at low temperature of less than 10 degrees centigrade and high pressure of from 50 KPA to 200 KPA. In a typical process, the milk product is pre-heat treated at a temperature of 80° C. to 138° C., followed by ultra-heat treatment from about 138° C. to about 150° C. in a holding tank, where it is held at a pressure of 700 KPA or an appropriate pressure. The carbonation may be achieved by direct injection of sterilized, purified carbon dioxide gas in a holding receptacle, or may be injected in line. Preferably the carbonation process is carried out at 20° C.±14° C. Then the carbonated liquid is transferred to a holding tank, where it is maintained at a pressure of 450 KPA and a temperature of 2° C. to 6° C.
In the patent U.S. Pat. No. 6,761,920, it is said that if, for some reason, the amount of carbonation of the pre-heated ultra heat treated milk product is insufficient, the product may be diverted to be reprocessed through the carbonator in a return loop to a holding tank to be re-pasteurized to be within the specification. After carbonation, the product is conveyed to a packaging station for packaging into sterile containers. The pH of the product is said to be preferentially maintained at 4.0 to 5.7 during packaging operations, depending on the product. After packaging the milk product into individual containers, it is said that the milk may be further sterilized by non-toxic radiation or pasteurization, however, no enabling description of how this would be done is provided.
Milk and dairy based products may provide an excellent environment for the growth and propagation of a wide spectrum of microorganisms. Pasteurization, by the application of heat for a specific time, has been the traditional method used for more than 100 years to prevent or reduce the growth of microorganisms and to increase the shelf life of milk and dairy based products. Pasteurization may not kill all microorganisms in milk and dairy products. However, it does reduce their numbers so they are unlikely to cause illness in the people consuming those products. Non-sterile dairy products, including pasteurized dairy products, typically have a shelf life that is limited to a short period of time such as a few weeks due to spoilage from the growth of microorganisms which survived pasteurization or were introduced by post-processing microbial contamination.
The traditional method of pasteurization was vat pasteurization, which involved heating the liquid ingredients in a large vat or tank for at least 30 minutes. Variations on the traditional pasteurization methods have been developed, such as, high temperature short time (HTST) pasteurization, ultra pasteurization (UP) processing, and ultra high temperature (UHT) pasteurization. These variations on the traditional pasteurization method use higher temperatures for shorter times, and may result in increased shelf lives which may exceed 3 months without refrigeration. However, regardless of the pasteurization method used, stabilizers and preservatives may often be needed to improve the stability of pasteurized products.
Thermal processing by any pasteurization method may have detrimental effects on the organoleptic and nutritional properties of milk and dairy based products. Thus, there may be a need for more non-thermal methods of extending shelf life, which will not significantly decrease or alter the organoleptic and nutritional properties of milk and dairy based products.
One alternative to pasteurization may be high pressure processing (HPP), which may be especially suited to high acid content foods. HPP is a food processing method where food products may be exposed to elevated pressures, in the presence or absence of heat, to inactivate microorganisms. HPP may also be known as high hydrostatic pressure processing (HPP) and ultra high-pressure processing (UHP).
Non-thermal HPP may be used to extend the shelf life of milk and dairy based products without detrimentally altering the organoleptic and nutritional properties of these products. Non-thermal HPP may eliminate thermal degradation, and may allow for the preservation of ‘fresh’ characteristics of foods. Shelf lives similar to those of pasteurized products may be achieved from HPP.
HPP of a milk or dairy based product may be achieved by placing the product in a container within a water (or other pressure-transmitting fluid) filled pressure vessel, closing the vessel, and increasing the pressure exerted upon the container by pumping more water into the pressure vessel by way of an external pressure intensifier. The elevated pressure may be held for a specific period of time, then it may be decreased. Pressure levels of about 600 MPa at 25° C. may typically be enough to inactivate vegetative forms of microorganisms, such as non-spore forming pathogens, vegetative bacteria, yeast and molds.
HPP is explained in more detail in U.S. Pat. No. 6,635,223 B2 to Maerz, issued Oct. 21, 2003, entitled “Method for inactivating microorganisms using high pressure processing”, wherein a method for inactivating microorganisms in a product using high pressure processing is disclosed. The method involves the steps of packing the product in a flexible container, heating the product to a pre-pressurized temperature, subjecting the product to a pressure at a pressurized temperature for a time period; and reducing the pressure after that time period. The method may also further comprise an additional step of subjecting the product to a predetermined amount of oxygen for a time interval. These methods may be applied to food, cosmetic or pharmaceutical products.
Carbon dioxide (CO2), a naturally occurring component of raw milk that decreases as raw milk is exposed to air or is pasteurized, is known to have antimicrobial properties. CO2 results in minimal harm in foods. Therefore, it is a suitable agent for inhibiting food spoilage microorganisms. Currently, there are at least three general mechanisms known by which CO2 inhibits microorganisms. These mechanisms, outlined briefly below, are discussed in more detail in an article by J. H. Hotchkiss et al., in Comprehensive Reviews in Food Science and Food Safety 2006; 5: 158-168, titled: “Addition of carbon dioxide to dairy products to improve quality: a comprehensive review”.
One mechanism by which CO2 may inhibit microbial growth may simply be by the displacement of O2 by CO2. Another mechanism by which CO2 may inhibit microbial growth may be by lowering the pH of the food by the dissolution of CO2 and formation of carbonic acid in the aqueous phase of the food by the following equilibrium reactions: H2O+CO2z,900 H2CO3H++HCO3−2H++CO32−. The third mechanism by which CO2 may inhibit microbial growth is by a direct effect of CO2 on the metabolism of microorganisms.
The last mentioned mechanism, the direct antimicrobial effect of CO2 on the metabolism of microorganisms, may be the result of changes in membrane fluidity due to CO2 dissolution, reductions in intracellular pH, and direct inhibition of metabolic pathways, including decarboxylation reactions and DNA replication. CO2 is quite lipophilic, which may allow for it to concentrate within the lipid membrane of bacteria, or to pass through the lipid membrane and to concentrate within the bacterial cell lowering intracellular pH. CO2 may also interfere directly with required enzymatic processes within microorganisms, such as gene expression.
Published European patent application. EP 0812544 A2 of Henzler et al., published Dec. 17, 1997, entitled “Method for preparing dairy products having increased shelf-life”, describes a method for preparing dairy products having increased shelf-life by incorporating CO2 into such products, comprising contacting a fluid milk fraction of a dairy foodstuff with CO2, mixing the fluid milk fraction and CO2 into a solution, and subjecting the solution to conditions sufficient to reach a steady state between the fluid milk fraction and dissolved CO2. The patented method is said to be adapted for consumer dairy products of a wide variety, increasing shelf-life to about 45 to about 60 days.
The interaction between HPP and CO2 and their effects on food spoilage enzymes and microorganisms were described by Corwin and Shellhammer in Journal of Food Science 2002; 67: 697-701, entitled “combined carbon dioxide and high pressure inactivation of pectin methylesterase, polyphenol oxidase, Lactobacillus plantarum and Escherichia coli.” The enzymes studied were pectin methylesterase (PME) and polyphenol oxidase (PPO) and the microorganisms studied were Lactobacillus plantarum ATCC 8014 (L. plantarum), an acid tolerant, lactic acid producing, non-spore forming, Gram positive bacterium, and Escherichia coli K12 (E. coli), an acid sensitive, non-spore forming, Grain negative bacterium. The objective of the study was to determine the effect of CO2 on increasing the efficacy of pressure processing to inactivate enzymes and microorganisms. CO2 was added at approximately 0.2 molar % to solutions processed at 500 to 800 MPa in order to further inactivate PME, PPO, L. plantarum, and E. coli. A significant interaction was found between CO2 and pressure at 25° C. and 50° C. for PME and PPO, respectively. Activity of PPO was said to be decreased by CO2 at all pressure treatments. Survival of L. plantarum was said to be decreased by the addition of CO2 at all pressures and the combination of CO2 and high pressure had a significant interaction. CO2 was said not to have a significant effect on the survival of E. coli under pressure.
U.S. Pat. Nos. 6,835,402 B1 and 6,866,877 B2 to Clark et al., issued Dec. 28, 2004 and Mar. 15, 2005, entitled, respectively: “Carbonated Fortified Milk-Based Beverage And Method For Suppressing Bacterial Formation In The Beverage” and “Carbonated Fortified Milk-Based Beverage And Method For Suppressing Bacterial Growth In The Beverage”, describe dairy or non-dairy based fortified carbonated beverage solutions that are said to supply essential nutrients in the human diet. In addition to describing the composition of a beverage, the patents disclose a method of using carbonization to reduce bacterial counts and reduce degradation of essential nutrients in milk-based beverages with or without pasteurization. In one embodiment, CO2 is added pre-pasteurization to eliminate or effectively reduce the growth of bacterial colonies in the beverage and reduce degradation of nutrients if UHT pasteurization is used. If CO2 is added pre-pasteurization, it is said that CO2 must be reintroduced, since pasteurization disseminates most CO2 present. This is done by in-line addition of CO2 after the beverage's temperature is brought down from about 185° F.-215° F. to about 40° F. It is said that the CO2 concentration in the final product is preferably from about 500 ppm to about 3,000 ppm. 1,000 ppm is said to be about 0.5 volumes of carbonation per volume of liquid beverage solution, so that the final product contains about 0.25 volumes to about 1.5 volumes of carbon dioxide per volume of liquid beverage solution. It is said this method increased the shelf life of the beverage by 10 days to over 75 days without refrigeration.
U.S. Pat. No. 7,041,327 B2 to Hotchkiss et al., issued May 9, 2006, entitled “Carbon dioxide as an aid in pasteurization”, describes processes to inhibit or reduce the growth of bacteria and other pathogens in a liquid by adding CO2 to the liquid, and thermally inactivating the bacteria and other pathogens, so that the CO2 enhances the thermal inactivation process. The process is said to be applicable to a wide variety of fluids, liquids, semi-solids and solids. Prior to or simultaneously with thermal inactivation CO2 is added to the product by sparging or bubbling, preferably to obtain levels of about 400-2000 ppm. At this level of CO2, the amount of microbial death that occurs during heating in a normal pasteurization (HTST) process is said to be increased by 10% to 90% over thermal inactivation carried out without the addition of CO2 prior to the thermal inactivation step. After completion of the thermal inactivation process, the free CO2 is said to be removed.
As is illustrated above, there are a number of different factors which need to be, or at least may be considered in development of a carbonated protein drink. At lease some of the references appear to teach away from each other in regard to, inter alia, 1) the concentrations of protein which can be used in a carbonated protein drink, 2) the amount of carbonation which can be used (and still enable a shelf-stable beverage), and 3) the pH at which various protein-containing carbonated beverages are shelf-stable.
There is also considerable lack of detail in the processing method steps described in at least some of the foregoing references, to the extent that one of skill in the art may not be enabled to produce a desired carbonated protein drink after experimentation, in view of the description. Inactivation of microbes, such as by thermal processing, after carbonation of the beverage may be a problem for at least some applications, requiring subsequent “recarbonation” to ensure that the beverage has the proper taste and mouth feel.